Internet protocol over WDM network, and packet communication system and method in the IPOW network

ABSTRACT

There is disclosed an internet protocol over WDM (IPOW) network structure which can directly route/transmit packets via a wavelength division multiplexing (WDM) optical communication network, and a packet transmission system in the network structure and method using the network structure. The internet protocol over wavelength division multiplexing (WDM) network structure comprising: a plurality of sub-ring for connecting n number of terminals (where n is a positive integer) to which unique user wave lengths are respectively allocated; a main ring for connecting n number of connection nodes connecting sub-rings to which unique user wave lengths are respectively allocated; a single sub-ring controller for controlling the flows of a packet transmitted/received inside the sub-ring and a packet transmitted/received between the sub-ring and the main ring; and a main ring controller connected to the single sub-ring and the main ring, and controlling the flow of a packet transmitted/received inside the main ring, wherein the terminals and connection nodes each add/drop only their own unique wavelength signals, the sub-ring controller and main ring controller drop all the wavelength division multiplexed signals to de-multiplex the signals, load each of the signals on their unique user wavelengths in their destination terminals, and then multiplex again the signals to transmit to the sub-ring and main ring, the sub-ring controller adds the identifying code (which is called a λ tag) of the sub-ring having a destination terminal, to the transmitted packet, and then transmits it to the main ring. The present invention has an advantage that it can route the packet at high speed, and also significantly simplifies a network structure. In addition, the present invention can process several tens of terabit traffic, expensive optical elements or optical systems, and a high-performance traffic routing apparatus such as a terra-bit level controller, etc.

TECHNICAL FIELD

[0001] The invention relates generally to an Internet Protocol (IP)which can directly route-transmit packets via a Wavelength DivisionMultiplexing (WDM) optical communication network. More particularly, thepresent invention relates to an Internet Protocol Over WDM (IPOW)optical communication network, a packet transmitting/receiving system inthe network and method using the network.

BACKGROUND OF THE INVENTION

[0002] A conventional method of routing/transmitting a packet will bebelow explained.

[0003] First, there is a TCP/IP (transmission control protocol/internetprotocol), which is a standard protocol for processing IP packets. AsTCP/IP is not limited by the type and size of LAN (local area network)and external networks connected to the LAN, there is an advantage thatit could be flexibly configured. Since it is impossible to expect thestructure of a network, however, IP addresses in all the nodes throughthe packet transverses must be translated for routing when a transferpath for a packet is established. Therefore, if it is desired thatinter-LAN transverse packets are routed/transmitted at high speed, thereare problems that the address system is complicated and the delay of thepacket transfer is increased.

[0004] Next, there is an SDH/SONET (synchronous digitalhierarchy/synchronous optical network), which is a representative methodused to transfer an IP packet via all optical transfer path. Moreparticularly, this method is one to transfer a SDH/SONET packet via anoptical transfer path in which an overhead defined by SDH/SONET protocolis added to the IP packet. However, there is a drawback that itstransfer efficiency is reduced since the amount of overhead added inSDH/SONET protocol hierarchy is great. Also, as the cost of theSDH/SONET apparatus is high, if it is used in a subscriber network foraccommodating internet subscribers, it adds a substantial cost to theservice providers and the subscribers. As well, as the transferequipment and the optical system which have the same capacity must beinstalled at entire networks for implementing a self-healing function inthe SDH/SONET apparatus, there are problems that it is nearly impossibleto extend the capacity of the networks depending on demand oncommunications or a substantial cost is required upon extension of thecapacity.

[0005] Then, there is an internet protocol in an asynchronous transfermode (ATM) over SDH/SONET. This method is one by which after ATM frameinformation is added to an IP packet, overhead information on SDH/SONETmust be added again in order to transfer the packet along the opticaltransfer path. This method, however, is the slowest method in thetransfer efficiency.

[0006] Finally, in an internet protocol over WDM scheme that is commonlyconsidered, if the total traffic is increased by terabit level, there isa problem that the routing processing capacity must be increased by theterabit level.

[0007] As mentioned above, there are advantages that the TCP/IP allows aflexible network configuration and the SDH/SONET or the ATM couldprovide various services through it. Due to flexibility of the networkconfiguration and its service, however, there is a problem that therouting and transfer efficiency of a packet is lowered. Also, theabove-mentioned schemes have a problem that they require expensiveoptical elements and systems such as OXC, OADM, wavelength converter,tunable LD, etc. so that they can be accommodated over WDM.

SUMMARY OF THE INVENTION

[0008] It is therefore an object of the present invention to provide aninternet protocol over WDM network structure, and a packettransmit/receive system and method using the same which can route andtransfer a packet at high speed in order to satisfy bandwidth andquality of service (QoS) being the core requirements in accommodatinginternet service. That is, the present invention is based on awavelength division multiplexing technology for internet service, whichis directed to supplement and comprise flexibility of networkconfiguration, diversity of services, and the routing and transferefficiency of packet.

[0009] In order to accomplish the above object, an internet protocolover wavelength division multiplexing (WDM) optical communicationnetwork structure according to the present invention is characterized inthat it comprises:

[0010] The internet protocol over wavelength division multiplexing (WDM)network structure comprising: a plurality of sub-ring for connecting nnumber of terminals (where n is a positive integer) to which unique userwave lengths are respectively allocated; a main ring for connecting nnumber of connection nodes connecting sub-rings to which unique userwave lengths are respectively allocated; a single sub-ring controllerconnected to the single sub-ring and the main ring, and controlling theflows of a packet transmitted/received inside the sub-ring and a packettransmitted/received between the sub-ring and the main ring; and a mainring controller for controlling the flow of a packettransmitted/received inside the main ring, wherein the terminals andconnection nodes each add/drop only their own unique wavelength signals,the sub-ring controller and main ring controller drop all the wavelengthdivision multiplexed signals to de-multiplex the signals, load each ofthe signals on their unique user wavelengths in their destinationterminals, and then multiplex again the signals to transmit to thesub-ring and main ring, and the sub-ring controller adds the identifyingcode (which is called a λ tag) of the sub-ring having a destinationterminal, to the transmitted packet, and then transmits it to the mainring.

[0011] Also, A sub-ring controller, in an internet protocol overwavelength division multiplexing network structure including the nnumber of terminals (where n is a positive integer) to which unique userwavelengths are respectively allocated, and a sub ring for connectingthe n number of terminals in a ring shape, comprising: a de-multiplexingmeans for dropping the wavelength division multiplexed signals passingthrough the sub-ring by wavelengths to de-multiplex the wavelengthdivision multiplexed signals; a routing means for establishing the pathof the de-multiplexed packet by the destination terminal, using thedestination terminal address included in the packet; a packet groupingmeans for grouping the packet for which its path is established by itsdestination terminal, a wavelength allocating means for loading thepacket grouped by its path on the unique user wavelengths of thedestination terminals; and a wavelength multiplexing means formultiplexing all the wavelength transformation signals for all thedestination terminals to transmit the multiplexed signals to thesub-ring.

[0012] Further, A main ring controller for receiving an extended packetto which a λ tag is attached front a source sub-ring controller totransmit the packet to a destination sub-ring controller, comprising: aλ-tag delineator for delineating a destination sub-ring using the λ-tagadded to the packets; a λ-tag based switching section for distributingthe packets by their destinations according to the λ-tag of thedestination terminal; at least n number of buffers for storing thepackets distributed according to the destination at the λ-tag basedswitching section; at least n number of lead frame sections for readingthe packets from each of the buffers and for adding the λ-tagcorresponding to the destination; and the n number of transmitters forreading the packets from each of the buffers to transmit the packetswith optical signals having wavelengths allocated to the destination.

[0013] Also, A method of transmitting/receiving packets in a sub-ringcontroller for controlling transmission/reception of the packets betweenany two of terminals, in an internet protocol over wavelength divisionmultiplexing (WDM) network including the n number of terminals (where nis a positive integer) to which unique user wavelengths are respectivelyallocated, comprising the steps of: if a source terminal transmitspackets containing destination terminal addresses on their own uniqueuser wavelengths, routing the paths of the packets by the destinationterminal addresses using the destination terminal addresses contained inthe packets; grouping the packets to be transmitted to the destinationterminals; and loading the grouped packets on the unique userwavelengths of the destination terminals and then transmitting thepackets to the sub-ring, whereby the destination terminal drops thegrouped packets.

[0014] Also, An internet protocol over wavelength division multiplexing(WDM) network structure comprising: the n number of terminals (where nis a positive integer) to which unique user wavelengths are respectivelyallocated; a single controller for controlling the flow of a packettransmitted between two terminals; and a ring network for connecting then number of terminals and the single controller in a ring shape, whereinwavelength division multiplexed signals are transmitted along the ringnetwork, wherein the terminals each add/drop only their own unique userwavelength signals among the wavelength division multiplexed signalstransmitted via the ring network, and the controller drops all thewavelength division multiplexed signals transmitted via the ring networkto de-multiplex the signals, loads each of the signals on their uniqueuser wavelengths in their destination terminals, and then multiplexesagain the signals to transmit to the ring network.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The aforementioned aspects and other features of the presentinvention will be explained in the following description, taken inconjunction with the accompanying drawings, wherein:

[0016]FIG. 1 is a sub-ring structure in an Internet Protocol OverWDM(IPOW) network according to one embodiment of the present invention;

[0017]FIG. 2 shows horizontally extended structures of two sub-rings;

[0018]FIG. 3 shows vertically extended structures of three sub-rings;

[0019]FIG. 4 shows one embodiment of a wavelength coupler, which isinstalled at each of the terminals in the sub-ring and at each of theconnection nodes in the main ring;

[0020]FIG. 5 is a functional block diagram of a sub-ring controlleraccording to one embodiment of the present invention;

[0021]FIG. 6 is a construction of a high-level network controlleraccording to one embodiment of the present invention; and

[0022] FIGS. 7 to 9 are simplified views of the horizontally extendedIPOW network in FIG. 2 for explaining a routing scheme in an internetprotocol over WDM network according to various embodiments of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

[0023] “An internet protocol over wavelength division multiplexing (WDM)optical communication network structure, a packet transmit/receivesystem in this network structure and method using the IPOW opticalcommunication network structure” according to one embodiment of thepresent invention, will be explained in detail by way of a preferredembodiment with reference to accompanying drawings.

[0024]FIG. 1 is a sub-ring structure in an internet protocol over WDM(hereinafter called “IPOW”) network according to one embodiment of thepresent invention.

[0025] The internet protocol over WDM network includes the m number ofconnection nodes (where m is a positive integer) to which unique userwavelengths are respectively allocated, a single main ring controller(MR-CN) for controlling the flow of a packet transmitted between giventwo of connection nodes, and a main ring for connecting said m number ofconnection nodes and said single main ring controller in a ring shape,wherein each of the connection nodes are connected to said sub-ring viasaid sub-ring controller (SR-CN).

[0026] The n number of terminals (where n is a positive integer) towhich unique user wavelengths are respectively allocated, and a singlesub-ring controller for controlling the flow of a packet transmittedbetween two terminals are connected to the sub-ring controller, and thesub-ring connects said n number of terminals and said single sub-ringcontroller in a ring shape, wherein wavelength division multiplexedsignals are transmitted along said sub-ring.

[0027]FIG. 2 illustrates an example of a network structure including amain ring and a single sub-ring in the IPOW network structure accordingto the present invention.

[0028] The network structure includes the m number of connection nodes(where m is a positive integer) 21 to which unique user wavelengths arerespectively allocated, a single main ring controller 22 for controllingthe flow of a packet transmitted between two connection nodes, and amain ring 23 for connecting the n number of connection nodes 21 and thesingle main ring controller 22 in a ring shape and along whichwavelength division multiplexed signals can be transmitted, wherein theconnection nodes 21 is connected to the sub-ring 26 via the sub-ringcontroller 24. Of course, n number of terminals may be connected to thesub-ring 26.

[0029] Each of the connection nodes 21 adds/drops only its own uniqueuser wavelength signal among wavelength division multiplexed signalsthat are transmitted via the main ring 23 since wavelength couplers aremounted. The main ring controller 22 drops all the wavelength divisionmultiplexed signals transmitted via the main ring 23 and thende-multiplexes the result. Then, it loads respective signals on theirunique user wavelengths in the connection nodes to which the sub-ringbelonging to their destination terminals is connected, multiplexes againthe signals and then transmits the multiplexed signals to the main ring23.

[0030] That is, m number of sub-rings is connected to this main ring,and m number of terminals is connected to respective sub-rings. In anIPOW network of a two-layer ring structure having these mainring/sub-rings, m×n number of terminals is connected. The main ring andthe sub-ring are connected via a sub-ring controller. The sub-ringcontroller is a connection point of the main ring and the sub-ring andis also responsible for relaying transmission/reception of a packetbetween the terminals and the main ring. The main ring controller is acontrol node for switching/transmitting inter-sub-ring packets betweenthe terminals connected to other sub-rings.

[0031] The network structure of the present invention has the followingfour prerequisites. First, all the sub-ring controllers shareinformation on IP addresses of all the terminals connected to the wholenetwork and the wavelength allocated to the sub-ring to which its IPaddress belongs. Second, all the terminals connected to a given sub-ringcommunicate with corresponding sub-ring controllers using differentwavelengths. The terminals connected to the different sub-rings,however, may reuse the same wavelength. Third, all the sub-ringcontrollers connected to the main ring communicate with the main ringcontroller using different wavelengths. Fourth, respective terminalscommunicate via the sub-ring controllers each of which is connected tothe sub-rings, respectively, and all the sub-ring controllerscommunicate via a single main ring controller managing them.

[0032] Above-mentioned structure of the sub-ring will now be explainedin detail.

[0033] This sub-ring includes the n number of terminals 11 (where n is apositive integer) to which unique user wavelengths are respectivelyallocated, a single sub-ring controller 12 for controlling the flow of apacket transmitted between two terminals, and a sub-ring 13 forconnecting the n number of terminals 11 and the single sub-ringcontroller 12 in a ring shape and along which wavelength divisionmultiplexed signals can be transmitted. To respective terminals may beconnected end users or a group of users. If the end user is connected,an optical network interface card is mounted. If the group users areconnected, an optical network interface unit is mounted.

[0034] Wavelength couplers, connected to the respective terminals,adds/drops only its own unique user wavelength signal among wavelengthdivision multiplexed signals that are transmitted via the sub-ring 13.The sub-ring controller 12 drops all the wavelength division multiplexedsignals transmitted via the sub-ring 13 to de-multiplex them. Then, itloads respective signals on their unique user wavelengths allocated totheir destination terminals, multiplexes again the signals and then addsthe multiplexed signal to the sub-ring 13.

[0035] In this IPOW network, a method of transmitting a packet betweenany two terminals will be explained as follows.

[0036] First, a method of transmitting a packet from a terminal i to aterminal j within a sub-ring will be explained as follows.

[0037] The terminal i generates a packet to be transmitted to theterminal j, adds/extends a source address and a destination address tothe packet, and then loads the extended packet on his unique usewavelength (λ₁). Then, the wavelength coupler in the terminal iadds/multiplexes the unique user wavelength on which the extended packetis loaded to the wavelength division multiplexed signal in the sub-ringto send it. The wavelength division multiplexed signal transverse thesub-ring and then drops to the sub-ring controller. Then, the sub-ringcontroller de-multiplexes the wavelength division multiplexed signal,loads it on the unique user wavelength g(λ_(j)) in the terminal j beingthe destination terminal, using the destination address included in thecorresponding packet, and then performs wavelength division multiplexingprocess for the de-multiplexed wavelength division signal along withother wavelengths to transmit the result to the sub-ring. The wavelengthcoupler in the terminal j drops only its own unique user wavelengthg(λ_(j)) among the wavelength division multiplexed signals that flowinto the sub-ring. By doing so, each of terminals belonging to the samesub-rings is transmitted by the sub-rings and the sub-ring controller,without traversing the main ring.

[0038] Next, referring to FIGS. 2 and 3, a method of transmitting apacket between terminals belonged to different sub-rings will beexplained as follows. FIG. 3 is a simplified view of the two-layer IPOWnetwork for explaining a routing scheme in an internet protocol over WDMnetwork according to one embodiment of the present invention.

[0039] As each of the terminals uses the wavelength allocated to itselfto communicate with the sub-ring controller, both the terminal and thesub-ring controller transmits an optical signal only in one direction,for example, only in a clockwise direction or an ant-clockwisedirection, so that wavelength collision does not occur within thesub-ring.

[0040] In case of the communication of each of the sub-ring controllerconnected to one main ring controller, each of the sub-ring controllersuses only the wavelength pre-allocated to itself to transmit/receiveoptical signal. Also, each of the sub-ring controllers transmits anoptical signal only in one direction, for example, only in a clockwisedirection or an ant-clockwise direction, so that wavelength collisiondoes not occur within the main ring.

[0041] As can be seen from FIG. 3, there is shown the state in which a jterminal in the sub-ring i transmits an optical signal to a l terminalin the sub-ring k. The n number of sub-rings is connected to theconnection nodes in the main rings via respective sub-ring controllersand the n number of terminals is connected to respective sub-rings. Thenumber of wavelength used in the entire network is n, and thewavelengths allocated to respective terminals and sub-ring controllersare as follows.

[0042] That is, the use wavelength of the sub-ring controller i is λ_(i)(where, i=1, . . , n), and the use wavelength of the terminals (i, j) isλ_(j) (where, j=1, . . . , n), wherein i is an index of the sub-ring andj is an index of the terminal. Therefore, the terminals (i, j) representthe j-th terminal connected to the i-th sub-ring.

[0043] Also, the arrows indicated dotted lines in FIG. 3 represent atransmit direction of the packet, and characters on the dotted linesrepresent wavelength used to transmit the packet. That is, the terminals(i, j) uses the wavelength gλ_(j) to transmit the packet to the sub-ringcontroller i and the sub-ring controller i uses the wavelength gλ_(l) totransmit the packet to the main ring controller. Meanwhile, in the mainring controller, the main ring transmits/receives an optical signal inwhich the wavelengths used by all the sub-ring controllers aremultiplexed in a clockwise direction but each of the sub-ringcontrollers receives only the optical signal loaded on the wavelengthallocated to itself. Also, in each of the sub-ring controllers, acorresponding sub-ring transmits/receives an optical signal in which thewavelengths used by all the terminals are multiplexed in a clockwisedirection but each of the terminals transmits/receives only the opticalsignal loaded on the wavelength allocated to itself.

[0044] For example, if there is a packet P from the terminals (i, j)toward the terminals (k, l), (where, k≠1, . . . , n, l=1, . . . n), theterminals (i, j) uses the wavelength gλ_(j) to the packet P to thesub-ring controller i.

[0045] Sub-ring controller i confirms destination address of the packetP by performing IP address comparison calculations. That is, as m×nnumber of terminals is connected in this IPOW network, totally n×nnumber of IP address comparison operations are performed. At this time,if the packet is transmitted/received between the terminals connected tothe same sub-ring, the corresponding packet is routed in thecorresponding sub-ring controller according to the existing internetprotocol, without being transferred to the main ring.

[0046] But, as the destination of the packet P is the terminal (k, l),the sub-ring controller j adds the identifying code k (which is called aλ tag) of the wavelength λ_(k) allocated to the sub-ring controller kand then loads the extended packet P+k on the wavelength gλ_(j) totransmit it to the main ring controller, This extended packet is loadedon the wavelength gλ_(l), experienced by wavelength divisionmultiplexing process along with wavelengths in the other connectionnodes, transmitted to the main ring and then dropped at the main ringcontroller.

[0047] Then, the main ring controller confirms the wavelengthidentifying code k of the extended packet P+k that is received via thewavelength λ_(i) and then loads the extended packet P+k on thewavelength λ_(k). Then, the main ring transmits the packet in aclockwise direction, the main ring controller performs a total m numberof wavelength identifying code comparison calculations to extract itssub-ring to which its destination terminal is connected.

[0048] The sub-ring controller packet k removes k from the packet P+k,conforms that its destination is the i-th terminal and then transmitsthe packet P on the wavelength gλ_(l) to transmit it the sub-ring k. Atthis time, the sub-ring controller n performs a maximum n number of IPaddress comparison calculations and then transmits the packet, with acorresponding wavelength, to the destination terminal.

[0049] As the terminal l receives only the optical signal loaded on thewavelength gλ_(l), the packet P generated at the terminals (i, j)arrives at the terminals (k, l). In addition, other terminals than theterminals (k, l) do not receive the packet P.

[0050] At this point, the signals transmitted to the main ring and thesub-ring are wavelength division multiplexed signals, where differentwavelengths are allocated to each of the connection nodes connected tothe main ring and different wavelengths are also allocated to each ofthe terminals connected to the sub-rings. In order for the n number ofwavelength used in any of the sub-rings to be reused in all thesub-rings, each of the sub-rings must accommodate the n number ofterminals and the n number of the sub-rings is connected to one mainring. By doing so, the number of wavelength used in the entire networkcan be minimized, and at the same time the number of terminals that canbe accommodated, can be maximized. That is, making the parameter m=n asmentioned above is a method of maximizing the efficiency of the network.In this case, a network structure, in which the n×n number of terminalscould be accommodated only using the n number of wavelength, is madepossible.

[0051] As mentioned above, in the internet protocol network according tothe present invention, each of the terminals communicates with a singlesub-ring controller and all the sub-ring controllers communicates via asingle main ring controller managing the sub-ring controllers. This isfor preventing a wavelength collision occurring at the time when the nnumber of wavelengths is reused by all the sub-rings.

[0052] A routing scheme using this wavelength identifying code is notapplied only to a nested ring structure as in the present invention butit can be applied to any networks satisfying the above-mentioned fourprerequisites. If the routing scheme using the wavelength identifyingcode proposed by the present invention is employed in the nested ringstructure proposed by the present invention, however, the number ofterminals that could be accommodated can be maximized using the limitfrequency and the most simplified structure can be made considering thesurvival of the network.

[0053] As aforementioned, the basis structure of the IPOW networkaccording to the present invention and a routing scheme using the λ tagin this network structure were explained, and then each of devices forestablishing the routing scheme will be explained as follows.

[0054] As mentioned above, a wavelength coupler is mounted to each ofthe terminals connected to the sub-ring and each of the connection nodesconnected to the main ring, which adds/drops only its own userwavelength allocated to himself.

[0055]FIG. 4 shows one embodiment of a wavelength coupler, which isinstalled at each of the terminals in the sub-ring and at each of theconnection nodes in the main ring. The wavelength coupler includes aninput circulator 41, a fiber Bragg grating 42 for reflecting unique userwavelength from corresponding terminal or connection node and passingother wavelengths, and an output circulator 43.

[0056] The input circulator 41 transfers the wavelength divisionmultiplexed signal inputted via the sub-ring or the main ring to thefiber Bragg grating 42, and also drops unique user wavelength from thecorresponding terminal or the connection node, which is reflected by thefiber Bragg grating 42. The output circulator 43 transfers the signaladded at the corresponding terminal or the connection node to the outputterminal of the fiber Bragg grating 42, multiplexes it along with thesignal passed through the fiber Bragg grating 42 and then transmit themultiplexed signal to the sub-ring or the main ring.

[0057]FIG. 5 is a functional block diagram of the sub-ring controlleraccording to one embodiment of the present invention.

[0058] Referring now to FIG. 5, the sub-ring controller is mainlydivided into a sub-ring managing section and a main ring managingsystem. The sub-ring section includes a de-multiplexer (AWG) 501 forde-multiplexing the wavelength division multiplexed signal from thesub-ring, a packet controller 502 for confirming the destination addressof each of the de-multiplexed signals and for transferring thede-multiplexed signal to a packet grouping section 503 if thedestination address belongs to the same sub-ring or transferring thede-multiplexed signal to a λ tag attachment section (ENCAP) 514 if thedestination address belongs to other sub-ring to route the path of thepacket, a packet grouping section 503 for grouping the packets forrespective destination addresses from the packet controller section 502,a wavelength allocating section 504 for loading the grouped packet onthe wavelengths allocated to each of the destination terminals, and amultiplexer (Coupler) 505 for performing a wavelength divisionmultiplexing for the signal to be transmitted to the respectivedestination terminals to transmit the result to the sub-ring.

[0059] The main ring managing section includes a light receiver 511 forreceiving only a signal having a corresponding wavelength via thewavelength coupler from the main ring, a lead frame section (Re-framer)512 for processing a signal including CRC (cyclic redundancy check), a λtag delineating section (DECAP) 513 for delineating a λ tag and fortransmitting a packet to the packet controller 502 in the sub-ringmanaging section, a λ tag attachment section 514 for attaching the λ tagreceived from the pack controller 502 in the sub-ring managing sectionto the packet to be transmitted, a lead frame section (Framer) 515 forcombining the λ tag with the packet to expand the combined packet, awavelength controller 516 for transforming the expanded packet into awavelength allocated to the corresponding connection node, and a lighttransmitter 517 for transmitting the expanded packet to the main ring.

[0060] If the source terminal and the destination terminal are connectedto the same sub-ring, a routine is possible when the packet is processedonly within the sub-ring managing section. If the source terminal andthe destination terminal are not connected to the same sub-ring, arouting is possible when the packet is processed both in the sub-ringmanaging section

[0061]FIG. 6 is a construction of a high-level network controlleraccording to one embodiment of the present invention, which is astructure for switching a packet at high speed.

[0062] The main network controller includes a λ-tag delineator 61, aλ-tag based switching section 62, buffers 63 each provided forwavelengths, respectively, a lead frame section 64 and a transmitter 65.The λ-tag delineator 61 delineates the λ-tags added to the packets Theλ-tag based switching section 62 distributes the packets to the buffers63 allocated to respective wavelengths based on the delineated λ-tag.The buffers 63 store the packets and each are provided for wavelengths,respectively. The buffers manage the packets based on the FIFO (first infirst out) priority or any priority policy if there is any specificpriority. The lead frame section 64 adds/transmits the λ-tag andinformation necessary for transmitting the packet if necessary. Thetransmitter 65 reads the packets from the buffers 63 to convert the readpackets into optical signals.

[0063] At this point, in respective control nodes, as the packets loadedon different wavelengths do not share the buffers and the transmitter,the time taken to manage the buffers can be shorten and the packet canbe transmitted with being loaded on a desired wavelength, withoutrequiring an expensive wavelength converting apparatus.

[0064] At this point, the main ring controller switches at high speedthe packet extended by the wavelength socket scheme. In other words, ifthe packet arrives at the main ring controller, the λ-tag delineator 61confirms the λ-tag added to the packet and the λ-tag based switchingsection 62 distributes the packet into the buffer allocated to thecorresponding wavelength according to the λ-tag. The buffers 63 aretemporarily the transmitted packet and the transmitter 65 reads thepacket from the corresponding packet and then loads the signal on thewavelength allocated to transmit it. At this time, if the sender triesto transmit the packet to the sub-ring control node to which thedestination belongs using the sub-ring control node connected, ifnecessary, the lead frame section 64 adds information necessary fortransmitting the packet in addition to the λ-tag of the correspondingdestination to transmit it.

[0065] As such, the wavelength socket scheme operates very simply. Asthe buffer and the transmitter are independently operated bywavelengths, however, the structure of the switch becomes simplified.Also, as additional wavelength transformer is not required, a stableoperation of the switch can be assured. Further, due to combination ofthe simple structure and the routing scheme using the λ-tag, the speedof the packet switching could be significantly improved.

[0066] As such, the wavelength socket scheme in which the buffer, thelead frame and the transmitter are provided for wavelengths is the coretechnology in developing a high-speed packet switch suitable for thewavelength division multiplexing network. The construction of the switchhas the following characteristics.

[0067] First, independent output buffers and transmitters are allocatedto respective wavelengths. Second, the output buffers allocated forrespective wavelengths can be independently managed in order to assureQoS (quality of service) for wavelengths. For example, considering onlytwo buffers, one buffer may be managed based on the FIFO priority andthe other buffer may be managed based on a given Heuristic algorithm.

[0068] The basic structure of the IPOW can be extended horizontally orvertically, and the sub-rings of FIG. 3 only can be extendedhorizontally. FIGS. 7 to 9 illustrates various embodiments of thenetwork structures.

[0069]FIG. 7 illustrates an horizontally extended embodiment of thebasic structure of the IPOW network shown in FIG. 3. In this structure,each connection nodes of two main rings is mutually connected by using agateway controller, and is connected to other main ring instead of thesub-ring. This gateway controller changes λ-tag transmitted from atransmitting part of the main ring into wavelength identifying code ofsaid sub-ring having destination terminal.

[0070] That is, referring FIG. 7, a flow of transmitting a packet to asub-ring j of a second main ring from a sub-ring i of the first mainring will be explained as follows. First, when packet (P₀) including anaddress of the destination terminal is transmitted from n number ofterminals of the sub-ring of the first main ring, the controller ofsub-ring i confirms that the destination terminal locates in sub-ring jof the second main ring, adds wavelength identifying code k according toconnection node k of the two main ring, loads the extended packet(P₀+k), and then transmits it to the controller of the second main ring.

[0071] The controller of the first main ring extracts and confirms thewavelength identifying code of the extended packet (P₀+k), and loads totransmit the extended packet (P₀+k). The extended packet (P₀+k) to λ_(k)drops from connection node k of the first main ring, and transmits it togateway controller. This gateway controller 71 removes λ-tag in theextended packet (P₀+k), confirms the address of destination terminal ofthe packet, adds the wavelength identifying code j according to sub-ringj having the destination terminal, and then loads the extended packet(P₀+k) to λ_(k), and then transmits it to the second main ring. Thecontroller of the second main ring loads and transmits the extendedpacket to gλ_(j) using the wavelength identifying code j of the extendedpacket, and the extended packet drops at the sub-ring j

[0072]FIG. 8 illustrates the basic structure of IPOW shown FIG. 3extended vertically according to an embodiment of the present invention.That is, sub-ring, intermediate ring, and main ring make a structure ofa three-layer structure. Said sub-ring controller 81 adds a first λ-tagg(λ₁) of the intermediate ring having destination terminal and a secondλ-tag (λ₂) of identifying code of said sub-ring, to the packet (P₀) fortransmitting, and then transmits extended packet. That is, said sub-ringcontroller attaches two λ-tags, and transmits to intermediate ring. Ofcourse, if said sub-ring controller intends to transmit the packet tothe sub-ring connected to the intermediate ring, the state of the firstλ-tag (λ₁) is null, and the second λ-tag (λ₂) adds to transmit thesub-ring identifying code having destination terminal.

[0073] Then, said intermediate ring controller 82 confirms a first λ-tagof said intermediate ring included in the extended packet transmittedfrom said sub-ring, and if a state of the first λ-tag is null, saidintermediate ring controller confirms identifying code of said sub-ring,and then transmits said extended packet to said sub-ring having saiddestination terminal, and if the state is not null, it transmits saidextended packet to said main ring. Then, said main controller 83confirms identifying code of said intermediate ring included in theextended packet transmitted from said intermediate ring, and thenchanges said identifying code of said intermediate ring into a nullstate, and then transmits said extended packet to said intermediate ringhaving said destination terminal.

[0074]FIG. 9 shows an example in which two sub-rings are horizontallyextended.

[0075] That is, any terminal in a first sub-ring and any terminal in asecond sub-ring are connected or two sub-rings share a single terminal,and the same unique user wavelength is allocated to two terminals in thesub-rings. FIG. 9 shows that a terminal j in the first sub-ring and aterminal j in the second sub-ring are connected to each other.

[0076] First, the terminal i in the first sub-ring generates a packet tobe transmitted to a terminal k in the second sub-ring, adds/extends asource address and a destination address to the corresponding packet,and then loads the extended packet on his unique user wavelength g(λ₁).Then, the wavelength coupler in the terminal j adds/multiplexes theunique user wavelength on which the extended packet is loaded, and thensends the multiplexed wavelength. The wavelength division multiplexedsignal transverses the first sub-ring and then drops to a first sub-ringcontroller. Then, the first sub-ring controller de-multiplexes thewavelength division multiplexed signal, loads it on the unique userwavelength g(λ_(j)) in the terminal j being the destination terminal,using the destination address included in the corresponding packet, andthe performs wavelength division multiplexing process for thede-multiplexing wavelength division signal along with other wavelengthsto transmit the result to the first sub-ring. The wavelength coupler inthe terminal j of the first sub-ring drops only its own unique userwavelength g(λ_(j)) among the wavelength division multiplexed signalsthat flow into the first sub-ring.

[0077] The terminal j in the first sub-ring passes the dropped signal tothe terminal j in the second sub-ring, and the terminal j in the secondsub-ring and adds/multiplexes it to the wavelength division multiplexedsignal in the second sub-ring to send the result. The wavelengthdivision multiplexed signal transverses the second sub-ring and thendrops to a second sub-ring controller. Then, the second sub-ringcontroller de-multiplexes the wavelength division multiplexed signal,loads it on the unique user wavelength (λ_(k)) in the terminal k beingthe destination terminal, using the destination address included in thecorresponding packet, and then performs wavelength division multiplexingprocess for the de-multiplexed wavelength division signal along withother wavelengths to transmit the result to the second sub-ring. Thewavelength coupler in the terminal k of the second sub-ring drops onlyits own unique user wavelength (λ_(k)) among the wavelength divisionmultiplexed signals that flow into the first sub-ring.

[0078]FIG. 2 shows that two sub-rings are horizontally connected to eachother, but other sub rings may be connected thereto via other terminals.

[0079]FIG. 3 is one embodiment for illustrating a network structure inwhich sub-rings are vertically extended.

[0080] In the IPOW network having this structure, a method of routing apacket from a sub-ring 1 to a sub-ring n (where n is a natural numbergreater than 1) will be below explained.

[0081] First, if a packet P, which is generated at a given terminalconnected to the sub-ring 1, arrives at the sub-ring controller 1, thesub-ring controller 1 confirms the destination address of the packet P.That is, as m×n number of terminals is connected in this IPOW network,totally n×n number of IP address comparison operations are performed. Atthis time, if the packet is transmitted/received between the terminalsconnected to the same sub-ring, the corresponding packet is routed inthe corresponding sub-ring controller according to the existing internetprotocol, without being transferred to the main ring.

[0082] As mentioned above, the present invention has the followingadvantages, compared to the technology of switching and transmitting anoptical signal using the conventional SDH/SONET protocol:

[0083] First, it can minimize additional information to be added to theIP packet in order to switch and transmit the optical signal. Also, ahigh-speed switching is made possible due to simplified packetstructure. Second, it does not require expensive optical element orsystems. Third, it can minimize the processing by electrical signal toimprove stability and performance of the network.

[0084] The present invention has been described with reference to aparticular embodiment in connection with a particular application. Thosehaving ordinary skill in the art and access to the teachings of thepresent invention will recognize additional modifications andapplications within the scope thereof.

[0085] It is therefore intended by the appended claims to cover any andall such applications, modifications, and embodiments within the scopeof the present invention.

What is claimed are:
 1. The internet protocol over wavelength divisionmultiplexing (WDM) network structure comprising: a plurality of sub-ringfor connecting n number of terminals (where n is a positive integer) towhich unique user wave lengths are respectively allocated; a main ringfor connecting n number of connection nodes connecting sub-rings towhich unique user wave lengths are respectively allocated; a singlesub-ring controller connected to said single sub-ring and said mainring, and controlling the flows of a packet transmitted/received insidesaid sub-ring and a packet transmitted/received between said sub-ringand said main ring; and a main ring controller for controlling the flowof a packet transmitted/received inside said main ring, wherein saidterminals and connection nodes each add/drop only their own uniquewavelength signals, said sub-ring controller and main ring controllerdrop all the wavelength division multiplexed signals to de-multiplex thesignals, load each of said signals on their unique user wavelengths intheir destination terminals, and then multiplex again said signals totransmit to said sub-ring and main ring, and said sub-ring controlleradds the identifying code (which is called a λ tag) of the sub-ringhaving a destination terminal, to the transmitted packet, and thentransmits it to said main ring.
 2. The internet protocol over wavelengthdivision multiplexing (WDM) network structure according to claim 1 ,wherein the number of the sub-rings connected to said main ring and thenumber of the terminals connected to one sub-ring are same (m=n), the nnumber of wavelengths g(λ₁˜λ_(n)) allocated to each of the sub-rings inthe main ring, and the n number of wavelengths g(λ₁˜λ_(n)) allocated toeach of the terminal in a given sub-ring are shared, whereby the n²number of terminals are supported by the n number of wavelengthsg(λ₁˜λ_(n)).
 3. The internet protocol over wavelength divisionmultiplexing (WDM) network structure according to claim 1 , wherein saidterminals and connection nodes include a wavelength coupler foradds/drops only its own unique user wavelengths.
 4. The internetprotocol over wavelength division multiplexing (WDM) network structureaccording to claim 1 , wherein said wavelength coupler includes an inputcirculator, a fiber Bragg grating for reflecting an unique userwavelength from a corresponding terminal and for passing otherwavelengths, and an output circulator, said input circulator transfersthe wavelength division multiplexed signal inputted via said sub-ring tosaid fiber Bragg grating and drops the unique user wavelength from thecorresponding terminal, that is reflected by said fiber Bragg grating,said output circulator transfers the signal added at the correspondingterminal to said output terminal of said fiber Bragg grating andtransmits said signal along with the signal passed through said fiberBragg grating to said sub-ring.
 5. In a sub-ring controller, an internetprotocol over wavelength division multiplexing (WDM) network structureaccording to claim 1 , comprising: a de-multiplexing means for droppingthe wavelength division multiplexed signals passing through saidsub-ring by wavelengths to de-multiplex the wavelength divisionmultiplexed signals; a routing means for establishing the path of thede-multiplexed packet by the destination terminal, using the destinationterminal address included in the packet; a packet grouping means forgrouping the packet for which its path is established by its destinationterminal; a wavelength allocating means for loading said packet groupedby its path on the unique user wavelengths of said destinationterminals; and a wavelength multiplexing means for multiplexing all thewavelength transformation signals for all the destination terminals totransmit the multiplexed signals to said sub-ring.
 6. An internetprotocol over wavelength division multiplexing (WDM) network structureaccording to claim 5 , wherein said packet grouping means include atleast n number of buffers for storing the packets discriminated by theirdestinations in said routing means.
 7. An interact protocol overwavelength division multiplexing (WDM) network structure according toclaim 5 , wherein said sub-ring controller includes: a λ tag attachmentmeans for attaching the λ tag according to the path of the packetdetermined by said packet routing means; a frame means for combiningsaid λ tag and said packet to expand the combined packet with adetermined transmission packet; a wavelength controller for transformingsaid expanded packet into its own unique user wavelength; and a lighttransmitter for transmitting into its own unique user wavelength signalof said expanded packet to said main ring.
 8. An internet protocol overwavelength division multiplexing (WDM) network structure according toclaim 5 , wherein said sub-ring controller includes: an optical receiverfor receiving the unique user wavelength signal from said main ring; areframe means for synchronizing said received signal and for receivingthe packet including CRC (cyclic redundancy check); and a λ tagdelineating means for delineating said λ tag to transmit the packet tothe routing means.
 9. An internet protocol over wavelength divisionmultiplexing (WDM) network structure according to claim 1 , comprising:a λ-tag delineator for delineating a destination sub-ring using theλ-tag added to the packets; a λ-tag based switching section fordistributing the packets by their destinations according to the λ-tag ofthe destination terminal; at least n number of buffers for storing thepackets distributed according to the destination at said λ-tag basedswitching section; at least n number of lead frame sections for readingthe packets from each of the buffers and for adding the λ-tagcorresponding to said destination; and the n number of transmitters forreading the packets from each of said buffers to transmit the packetswith optical signals having wavelengths allocated to said destination.10. The internet protocol over wavelength division multiplexing (WDM)network structure according to claim 1 , wherein said main ring isextended horizontally by connecting n number of said connection nodes ofsaid main ring and n number of connection nodes of another main ring bymeans of gateway controller, a transmitting part of said sub-ringcontroller adds an identifying code (λ-tag) of the connection node to apacket for transmitting, and then transmits it to a transmitting part ofsaid main ring, said gateway controller transforms an identifying codeof said packet into identifying codes of said connection nodes connectedwith a receiving part of said sub-ring, and then transmits it to areceiving part of said main ring.
 11. An internet protocol overwavelength division multiplexing (WDM) network structure according toclaim 1 , wherein a plurality of intermediate rings connected with theplurality of said sub-rings make a structure of a three-layer structureby connecting with said main ring, said intermediate ring havingintermediate ring controllers for controlling a path of the packettransmitted from said sub-rings or said main ring, said sub-ringcontroller adds identifying code of the intermediate ring havingdestination terminal and identifying code of said sub-ring, to thepacket for transmitting, and then transmits extended packet, saidintermediate ring controller confirms identifying code of saidintermediate ring included in the extended packet transmitted from saidsub-ring, and if a state of the identifying code is null, saidintermediate ring controller confirms identifying code of said sub-ring,and then transmits said extended packet to said sub-ring having saiddestination terminal, and if the state is not null, it transmits saidextended packet to said main ring, and said main controller confirmsidentifying code of said intermediate ring included in the extendedpacket transmitted from said intermediate ring, and then changes saididentifying code of said intermediate ring into a null state, and thentransmits said extended packet to said intermediate ring having saiddestination terminal.
 12. A sub-ring controller, in an internet protocolover wavelength division multiplexing network structure including the nnumber of terminals (where n is a positive integer) to which unique userwavelengths are respectively allocated, and a sub ring for connectingthe n number of terminals in a ring shape, comprising: a de-multiplexingmeans for dropping the wavelength division multiplexed signals passingthrough said sub-ring by wavelengths to de-multiplex the wavelengthdivision multiplexed signals; a routing means for establishing the pathof the de-multiplexed packet by the destination terminal, using thedestination terminal address included in the packet; a packet groupingmeans for grouping the packet for which its path is established by itsdestination terminal; a wavelength allocating means for loading saidpacket grouped by its path on the unique user wavelengths of saiddestination terminals; and a wavelength multiplexing means formultiplexing all the wavelength transformation signals for all thedestination terminals to transmit the multiplexed signals to saidsub-ring.
 13. The sub-ring controller according to claim 12 , whereinsaid packet grouping means include at least n number of buffers forstoring the packets discriminated by their destinations in said routingmeans.
 14. The sub-ring controller according to claim 12 , wherein theinternet protocol over wavelength division multiplexing (WDM) networkincludes: a main ring along which the path of the wavelength divisionmultiplexing signal transverses, and a sub-ring connected via saidsub-ring controller to a plurality of connection nodes in said main ringto which unique user wavelengths are allocated, respectively, saidsub-ring controller for adding an unique user wavelength information (λtag) on the destination sub-ring to a packet to be transmitted from itsown sub-ring to other sub-ring and then for transmitting the packet tosaid main ring, in order to communicate with other sub-rings connectedto said main ring, includes: a λ tag attachment means for attaching theλ tag according to the path of the packet determined by said packetrouting means; a frame means for combining said λ tag and said packet toexpand the combined packet with a determined transmission packet; awavelength controller for transforming said expanded packet into its ownunique user wavelength; and a light transmitter for transmitting intoits own unique user wavelength signal of said expanded packet to saidmain ring.
 15. The sub-ring controller according to claim 8 , whereinthe internet protocol over wavelength division multiplexing (WDM)network includes: a main ring along which the path of the wavelengthdivision multiplexing signal transverses, and a sub-ring connected viasaid sub-ring controller to a plurality of connection nodes in said mainring to which unique user wavelengths are allocated, respectively, saidsub-ring controller for delineating a λ tag from the signal receivedfrom said main ring to transmit the signal to the destination terminal,in order to communicate with other sub-rings connected to said main ringincludes: an optical receiver for receiving the unique user wavelengthsignal from said main ring; a lead frame means for synchronizing saidreceived signal and for receiving the packet including CRC (cyclicredundancy check); and a λ tag delineating means for delineating said λtag to transmit the packet to the routing means.
 16. A main ringcontroller for receiving an extended packet to which a λ tag is attachedfrom a source sub-ring controller to transmit the packet to adestination sub-ring controller, comprising: a λ-tag delineator fordelineating a destination sub-ring using the λ-tag added to the packets;a λ-tag based switching section for distributing the packets by theirdestinations according to the λ-tag of the destination terminal; atleast n number of buffers for storing the packets distributed accordingto the destination at said λ-tag based switching section; at least nnumber of lead frame sections for reading the packets from each of thebuffers and for adding the λ-tag corresponding to said destination; andthe n number of transmitters for reading the packets from each of saidbuffers to transmit the packets with optical signals having wavelengthsallocated to said destination.
 17. A method of transmitting/receivingpackets in a sub-ring controller for controlling transmission/receptionof the packets between any two of terminals, in an internet protocolover wavelength division multiplexing (WDM) network including the nnumber of terminals (where n is a positive integer) to which unique userwavelengths are respectively allocated, comprising the steps of: if asource terminal transmits packets containing destination terminaladdresses on their own unique user wavelengths, routing the paths of thepackets by the destination terminal addresses using the destinationterminal addresses contained in the packets; grouping the packets to betransmitted to the destination terminals: and loading the groupedpackets on the unique user wavelengths of the destination terminals andthen transmitting the packets to the sub-ring, whereby said destinationterminal drops said grouped packets.
 18. The method oftransmitting/receiving packets in an internet protocol over wavelengthdivision multiplexing network according to claim 17 , wherein saidrouting step including delineating the packets by their destinationterminals, said grouping step including temporarily storing the packetsin the buffers allocated to the destination terminals of the packets.19. The method of transmitting/receiving packets according to claim 17 ,wherein a plurality of connection nodes of sub-ring connected via a mainring along which the path of the wavelength division multiplexing signaltransverses, the method in said sub-ring controller for adding an uniqueuser wavelength information (λ tag) on the destination sub-ring to thepacket to be transmitted from its own sub-ring to other sub-ring totransmit the packet to said main ring, includes: a λ tag attachment stepof attaching for attaching the λ tag according to the path of the packetdetermined at the step of routing the packet; a frame step of combiningthe λ tag with the packet to expand the packet as a determinedtransmission packet; a wavelength allocating step of loading theexpanded packet on it own unique user wavelength; and a lighttransmission step of transmitting the expanded packet loaded on its ownunique user wavelength to the main ring.
 20. The method oftransmitting/receiving packets according to claim 17 , wherein aplurality of connection nodes of sub-ring connected via a main ringalong which the path of the wavelength division multiplexing signaltransverses, the method in said sub-ring controller for delineating theλ tag from the signal received from said main ring to transmit thesignal to the destination terminal, includes: a light receiving step ofreceiving the unique user wavelength signal from said main ring, areframe step of synchronizing the received signal and for receiving thesignal including CRC; and a λ tag delineating step of delineating the λtag to transmit the packet to the routing step.
 21. The method oftransmitting/receiving packets according to claim 19 , wherein the mainring controller for receiving the expanded packet to which the λ tag isattached from the source sub-ring to transmit the packet to thedestination sub-ring, includes: a λ-tag delineation step of delineatingthe destination sub-ring using the λ-tag contained in the packetsinputted; a λ-tag based switching step of distributing the packets bytheir destinations according to the λ-tag of the destination terminal; abuffering step of storing the packets distributed according to thedestination in said λ-tag based switching step on buffers; a reframestep of reading the packets from the buffers and then for adding again aλ-tag corresponding to said destination; and a transmission step oftransmitting the lead framed packets with optical signals havingwavelengths allocated to said destination.
 22. An internet protocol overwavelength division multiplexing (WDM) network structure comprising: then number of terminals (where n is a positive integer) to which uniqueuser wavelengths are respectively allocated; a single controller forcontrolling the flow of a packet transmitted between two terminals; anda ring network for connecting said n number of terminals and said singlecontroller in a ring shape, wherein wavelength division multiplexedsignals are transmitted along said ring network, wherein said terminalseach add/drop only their own unique user wavelength signals among thewavelength division multiplexed signals transmitted via said ringnetwork, and said controller drops all the wavelength divisionmultiplexed signals transmitted via said ring network to de-multiplexthe signals, loads each of said signals on their unique user wavelengthsin their destination terminals, and then multiplexes again said signalsto transmit to said ring network.
 23. The internet protocol overwavelength division multiplexing (WDM) network structure according toclaim 22 , wherein any one terminal belonging to said ring network andany one terminal belonging to other ring network are connected, the sameunique user wavelength is allocated to said two terminals, whereby ascommunication between said two ring networks are made possible via saidtwo terminals, said ring networks are horizontally extended,respectively.
 24. The internet protocol over wavelength divisionmultiplexing (WDM) network structure according to claim 22 , whereinsaid terminals includes a wavelength coupler for adds/drops only its ownunique user wavelengths, said wavelength coupler including an inputcirculator, a fiber Bragg grating for reflecting an unique userwavelength from a corresponding terminal and for passing otherwavelengths, and an output circulator, wherein said input circulatortransfers the wavelength division multiplexed signal inputted via saidsub-ring to said fiber Bragg grating and drops the unique userwavelength from the corresponding terminal, that is reflected by saidfiber Bragg grating, and said output circulator transfers the signaladded at the corresponding terminal to said output terminal of saidfiber Bragg grating and transmits said signal along with the signalpassed through said fiber Bragg grating to said sub-ring.